Gauge for indicating pressure increase caused by heat in tires



Oct. 21, 1952 D. H. WELSH ETAL GAUGE FOR INDICATING PRESSURE INCREASE CAUSED BY HEAT IN TIRES Filed NOV. 4, 1949 I 2 SHEETS-SHEET 1 INVENTORS 014 6 #42 s Oct. 21, 1952 WELSH r 2,614,429

GAUGE FOR INDICATING PRESSURE INCREASE CAUSED BY HEAT IN TIRES Filed NOV. 4, 1949 2 SHEETS-SHEET 2 IN V EN TORS I014 /7f /%-'16// y 200 19. #54445 mxmw Patented Oct. 21, 1952 r crews;

GAUGE FOR INDICATING PRESSURE IN- CREASECAUSED BY HEAT IN TIRES Dolan .H. Welsh and EldonA. Means, Wichita, Kane; said Means assignor to said Welsh Application November 4, 1949, Serial No. 125,598

1 6 Claims.

The invention herein disclosedisa. ease for showing thepressure developed by' heat in a tire.

'l'he' ordinary tire-gage shows actual. pres. sure, regardless of temperature; If :atire .ischot this pressure may behigherythan is proper, for thattire and yet, actually, the? tire be under inflated.

A tire* with insufficient pressure. will heat rapidly and thus build up.a.pressurerwhich: on an ordinary tire gage will indicate over inflation."

' On'testing such: a tire; with this:v reading of too-high pressure, thecorrectivetendency would be :toletioutsome air and thusfurther aggravate the heat developing condition .oiunder inflation.

Thepresentiinventicn aims to: overcome and prevent'tsuch dangerous conditions; i

' Particularly it is a purpose cof the invention 170T? provide; an: instrument'which will .show at once'the' temperature-pressure condition in aJtire and thus? provide instant information as' to Whether. a tire is riding 'normallyor. requires pressure correction one way or. another.

" Attendantobjects of .the invention'are toprovide' such instrument in a handy, practical form which .willbe convenient to. use and therefore acceptable to service station attendants and others :who: usually attend to the conditions.-

Additional objects of .the invention are'to pro-- vide such an instrument ina sturdy form of construction which will stand the handling'to which it may be subjected and whichwith all its advantages, will be a relatively lowgcostlitem.

Important objectsofthe invention are to assure-accuracy and reliability, and tothis end itis" further intended that this new gage be made up ofrelatively few; simple parts.

Other desirable objects'andthe novel features through whichthe' purposes of the invention are attained'are set forth or will appear in the course of the following specification.

' "iIhe drawings accompanying. and forming part of." the. specification illustrate certain present practical .embodii'nentsof the invention. Actual structure, however, may he .iurther. modified and changed asmregards, the immediate illustration, all within. theftrue intentand broad. scopeQof the-invention. as hereinafter. defined and. claimed.

Fig. Lin. thedrawings is a. broken .side elevation.of one-of.thenew gageswith portions at a the :lowenandixpper ends broken. away and apgearing, in: section ..to show the hot junction and coldojunctionends; respectively, 1 of. .therthermos couple which ,isprovidedi torsense the tempera- Fig. 3,.is anenlarged broken sectiona'lfldetall of the upperor cold junction end of :the :instru: ment;.

Fig. 4 isa'cross, sectional detail. as :on substan: tially theplane of, line 4+4. of Fig. 3, shQWing thespool or spreader for the cold junction ends ofthe thermocouple;

Fig. 5 is: an; enlarged; plan view of, one-of the insulating holders. 1 for the'lower; hot junction ends. of the thermocouple;

Fig. 6 is a general wiring dia ram;

Fig. 7 is agraphic wiring diagram showingthe parts more nearly asthey-are actually-disposed in the instrument;

Fig. 8 isfla similar view showing a simplified iormofwiring system and usingonebranchoi the double-ended air chuck for thecold junc; tions of a. thermocouple; while the other end is. used for the hot junctions.

The device is shownin Fig. 1' as a hand tool having an elongated tubular handle Ill terminating at'the lower endin-anangularly disposed tubular head, H carrying air chucks l2, l3, at its opposite ends disposed for use, respectively, with ordinary tires or with the less accessible dual trucktires. Each of these air chucks comprises in the illustration, an insulating sleeve 14 having: a valvestem engaging stud liat the.

trated, (Fig. 6), of companion, dissimilar wires I I9, 28; such as copper and Constantan, each pair connected together at one end as at 8, to form the hot junctions, and connected, together at their opposite ends to formpthe cold junctions 2|.

In order that this thermocouple be instantly susceptible andresponsive to temperature con; ditions, very fine wires, may be used and the hot and cold junction ends be disposedwhererthey 'will be immediately effected by tire temperature and by the normal ambient air conditions; respectively.

In .the illustration the hot junctions H! are supported inopenings; 22; in; the, insulator; i! so, as: to stand free in spaced relation inthe inner end of the screw socket [B in the insulating sleeve I4, where they will be subjected to hot air from the tire released through the small pasgaskets 28 sealing these parts air-tight and pro- I viding air-tight seals for engagement over the ends of the tubular tire valves.

The upper, cold junction ends of the thermocouple wires are spaced in separated relation in the illustration, by an insulating spool or spider 4 is depressed by the stud [5 to admit tire air through passage 23 direct to the hot junctions I8. This air is permitted to slowly escape through vents 24, 25, Fig. 2, so that these junctions are immediately subjected to the true internal air temperature of the tire. This venting of air past the junctions, however, is so slight as not to bleed the tire to any appreciable extent; Also, the wires are so fine that the reaction is practically instantaneous, or at least withoutappreciable delay.

Consequently, the instrument will give apractically immediate reading showing, for instance, as in the present example, the number of points accumulated in the tire through temperature rise.

The actualincrease in temperature may have been occasioned by long continued rough'riding,

29 having slots 30, Figs. 3 and 4, holding and supporting the cold junction ends 2|.

This last mentioned insulating spacer is shown as removably secured in position over the upper end of the handle by a hollow screw cap 3 I, ported inth'e'sides at 32 to freely admit cooling air to the coldjunctions.

A quick reading indicator is preferably provided, shown here in the form of a millivoltmeter 33, suitably calibrated at 34 in terms of excess air temperature created pressure Values.

- This indicator responds to potential developed by the thermocouple and since the pressure increase directly corresponds to temperature increase, the scale may be laid off in pounds so that an observer may read directly the number of'pounds'developed by temperature in the tire. A reverse throw switch 35 provided in the wir-' ing connections 36 enables the indicating instrument to be connected selectively with the hot junctions 18 of either the downwardly or the upwardly faced air chucks I3.

While the indicator or gage instrument 33 is shown connected with the thermocouple by a cablef36, it is contemplated that this instrument may be directly mounted on the handle.

Fig. '7 shows diagrammatically how, when the lower air chuck I2 is used, the switch 35 may be shifted to the right to connect the lowermost set of hot junctions at the air chuck I2 in circuit with'the gage instrument 33, and be shifted to the left to connect the hot junctions of the upper chuck I3 in circuit with the indicating instrument.

The arrangement disclosed, with the hot junctions at the lower end and the cold junctions at the upper end of the handle, provides desirable spacing of the opposed junctions.

It is contemplated, however, that this spacing -may be effected by the distance between the alternately usable air chucks l2 and [3, as shown diagrammatically in Fig. 8- where, when one 'chuck suchas I2 is in use, the junctions [8a .thereat will operate as hot junctions and the. junctions zmat the open chuck I 3 will serve as cold junctions.

In such a construction a switch may be prov'i'dedto cut the indicating instrument reversely 'into proper operating relation to the thermocouple or, asshown in Fig. 8, a double reading instrument '33am'ay be directly connected by wires 3'! to opposite ends of the thermocouple, with the pointer swinging in one direction for one chuck and in the opposite direction for the other chuck. To use the instrument it is only necessary to pressoneof the air chucks tightly over the end .-';of the tire'valve, In this actthe stem of the valve under inflation, misalignment or the like. In any event, the operator is informed that there is an accumulation of pressure due to increase of temperature above that of normal pressure and run-- ning conditions. 1

To assume an example, it may be considered that the instrument, when applied to a tire designed for 24 pounds pressure, shows a temperature-pressure increase of 10 pounds. The pressure on an ordinar tire gage'may show at that time, say, 30 pounds. This means that 10 pounds have been accumulated by heat in the tireand that actually the tire is under' inflated, instead of being overinflated, as the tire gage indicates. This'conclusion is arrived at by deducting-the 10 pounds of heat accumulated pressure from the 30 pounds actual, leaving only .20 pounds as the initial or normal pressure, an under inflation of 4 pounds, informing the operator that instead of releasing 6 pounds to bringthe tire down to 24,

actually he should put in 4 pounds tobring the tire up to the normal 24 pounds it was designed for. By these deductions the tire," instead of being further injured by further under inflation, is, by the addition of 4 pounds extra pressure-,,

quiredfor restoring proper pressure conditionsfor the tire.

What is claimed is:

1. A gage for indicating the'pressure rise due to temperature increase in a tire, comprising ,an

air chuck for engagement over a tire valve and arranged to efiect sampling of the tire-contained air, said air chuck having a c'hamberarranged to receive the sample air taken from the tire, a

thermocouple carried by said air chuck and hav- A ing a hot junction in saidchamber and positioned for contact bythe' sampled air extracted from the j tire and a cold junction positioned for'contact by atmospheric air, and an electric potential instrument connected with said thermocouple and calibrated in terms of thermal-pressure increase.

2. A gage forindicating the pressure rise due to temperature increase in a tire, comprising an air chuck forengagement over a tirevalve'and arranged to effect sampling ofthe tire-contained air, said airchuck having a chamber arranged to receive the sample air taken' from the tire; a thermocouple carried by said air chuck and hav .ing a hot junction in said chamber and positioned for-contact by the sampled air'extractedzfrom the tire and a cold junction positioned for contact by atmospheric air, and an electric potential instrument connected with said thermocouple and calibrated in terms of thermal-pressure increase, said thermocouple including a plurality of hot and cold junctions of fine wire supported in spaced apart relation and said chamber having a small vent to atmosphere for letting hot air sampled from the tire past the hot junctions located in said chamber.

3. A gage for indicating the pressure rise due to temperature increase in a tire, comprising an air chuck for engagement over a tire valve and arranged to effect sampling of the tire-contained air, said air chuck having a, chamber arranged to receive the sample air taken from the tire, a thermocouple carried by said air chuck and having a hot junction in said chamber and positioned for contact by the sampled air extracted fromthe tire and a cold junction positioned for contact by atmospheric air, and an electric potential instrument connected with said thermocouple and calibrated in terms of thermal-pressure increase, said gage having selectively usable air chucks faced in opposite directions and the hot and cold junctions of said thermocouple being disposed in said oppositely faced air chucks and alternately operative as hot and cold junctions, dependent upon which air chuck is applied to a tire valve.

4. A gage for indicating the pressure rise due to temperature increase in a tire, comprising an air chuck for engagement over a tire valve and same in spaced apart relation, said plug having a passage therethrough for venting the sampled air past the supported ends of the wires.

5. A gage for indicating the pressure rise due to temperature increase in a tire, comprising an air chuck for engagement over a tire valve and arranged to eifect sampling of the tire-contained air, said air chuck havin a chamber arranged to receive the sample air taken from the tire, a thermocouple carried by said air chuck and having a hot junction in said chamber and positioned her.

6. A gage for indicating pressure rise due to temperature increase in a tire, comprising an air chuck having an insulating sleeve provided with a valve stem operating stud at the outer end, a socket at the inner end and an air sampling passage extending from said stud to said socket, an insulating plug entered in said socket and having passages therethrough, a thermocouple composed of wires supported in certain of said passages and having hot junction ends supported thereby within said socket, one of said passages being open to pass tire sampled air through said plug, said thermocouple having cold junctions exposed to cooler air and a potential sensing indicator connected with said thermocouple and calibrated in terms of thermal-pressure values.

DOLAN H. WELSH. ELDO-N A. MEANS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

